Jörg Hübscher

Intermolecular contacts in the crystal structures of specifically varied halogen and protonic group substituted azines

A series of azines featuring differently halogen and protic group substituted pyridine, pyrimidine and pyridazine compounds have been synthesized and studied in terms of their crystal structures in order to develop a better understanding of the links between structural conditions and molecular packing behavior. Complemented by the structure results of related compounds known from the literature, intermolecular contact relationships connected to the present substance types were found, having potential use in future crystal engineering of similar compounds. This primarily involves the formation of N⋯I contacts aside from specific halogen⋯halogen and hydrogen bond type interactions.

Synthesis and Structural Characterisation of New Bifunctional o-Hydroxyacetophenones – Potential Linker Molecules for Coordinative Framework Construction

Two new linker-type molecules 1a and 1b composed of o-hydroxyacetophenone coordinative groups attached to linear ethynylene or 1,4-phenylenediethynylene spacer units have been synthesised and structurally characterised. An X-ray crystallographic study for both compounds has shown structures with strong intramolecular hydrogen bonds fitting in the model of ‘Intramolecular Resonance Assisted Hydrogen Bond (IRHAB)’. Initial coordination experiments with Cu(II) were performed and the resulting materials characterised by PXRD. The similarity of the copper coordination between these compounds and copper(II) acetylacetonate complexes was demonstrated by XPS measurements. Based on the evidence of these studies, and on elemental analysis, the formation of the corresponding coordination polymers comprising Cu(II) and the linkers has been proposed Graphical Abstract Synthesis and Structural Characterisation of New Bifunctional o-Hydroxyacetophenones – Potential Linker Molecules for Coordinative Framework Construction

The m-phenylene-bridged bis-oxazole 4,4',5,5'-tetraphenyl-2,2'-m-phenylenedi-1,3-oxazole and its bulkily substituted analogue 4,4',5,5'-tetrakis(4-tert-butylphenyl)-2,2'-m-phenylenedi-1,3-oxazole.

The title m-phenylene-bridged bis-oxazoles, C(36)H(24)N(2)O(2), (I), and C(52)H(56)N(2)O(2), (II), feature different aryl substituents in the 4- and 5-positions of the oxazole units. In the solid state, aside from the different twist of the peripheral aryl rings, the molecules show distinctly different conformations, with anti and syn orientations of the O and N atoms for (I) and (II), respectively. Connected with this property, in the crystal structure of (I), extensive π-stacking is found between the molecules, while the crystal structure of (II) only involves dimer formation as the prominent packing motif.

Crystal structure of 2-chloro-5-(3-hy­droxy-3-methyl­but-1-yn-1-yl)pyrimidine

The ethynylpyrimidine moiety displays an almost planar geometry. In the crystal, molecules are linked by O—H⋯N and C—Hpyrimidine⋯O hydrogen bonds, forming a three-dimensional supramolecular architecture.

Crystal structure of a new polymorph of di(thio­phen-3-yl) ketone

A new polymorph of di(thiophen-3-yl) ketone differing from the previous structure by the molecular assembly is reported and comparatively discussed.

Crystal structures of 2-acetyl-4-ethynylphenol and 2-acetyl-4-(3-hy­droxy-3-methylbut-1-yn-1-yl)phenol

Crystal structures of two 4-substituted derivatives of 2-acetylphenol are discussed comparatively with reference to modes of hydrogen bonding.

X-ray crystal structures of solvated bisimidazole derivatives including a half-way analogous lophine-type compound

Abstract The tetrachloro and tetrabromo substituted bisimidazoles 1,4-bis(4,5-bis(4-chlorophenyl)-1H-imidazol-2-yl)benzene (1) and 1,4-bis(4,5-bis(4-bromophenyl)-1H-imidazol-2-yl)benzene (2), respectively, as well as a corresponding aldehydic intermediate imidazole 4-(4,5-bis(4-bromophenyl)-1H-imidazol-2-yl)benzaldehyde (3) have been synthesized. Respective solvated complexes [1 DMSO (1:2)] (1a), [2 (1,4-dioxane) (1:5)] (2a) and [3 DMSO · H2O (1:1:1)] (3a) were isolated and structurally studied by single crystal X-ray diffraction. Although the central three-membered ring systems in 1 and 2 are almost coplanar, there is no relevant stacking between the molecules. However, 1 and 2 show a distinct difference in conformation with respect to the orientation of the imidazole rings which is cisoid in 1a and transoid in 2a, being attributed to the specific solvent interactions. Hydrogen bonds of N—H···O, C—H···O and C—H···π type are found in all structures while Cl···Cl contacts are characteristic of 1a, Br···O and C—H···Br of 2a, and O—H···O and Br···Br contacts of the crystal structure of 3a. Owing to the formation of solvated crystals, especially the compounds 1 and 2 are represented as potential new inclusion hosts.

New Pyridylene-bridged Bisoxazoles - Synthesis and Structural Study

The bisoxazoles 1a - 1c that feature structures with two oxazole moieties connected to a 2,6- pyridylene central linker and contain different aryl substituents in 4- and 5-positions of the oxazole rings have been synthesized. Single-crystal X-ray structure determinations of the free ligand 1a, containing the NiCl2 complex of 1c as the CH3COOH solvate as well as the 1,4-dioxane-solvated diester intermediate 2a are reported, which show specific molecular conformations and packings in the crystals. The conformation of 1a is syn with reference to the oxazole nitrogen atoms and anti with reference to the oxazole and pyridine nitrogen atoms. In the Ni2+ complex, the metal ion is in an octahedral coordination environment with the nitrogens of 1c and an oxygen of an acetic acid molecule in the basal plane, while two chloride ions occupy the axial positions of three additional acetic acid molecules one is hydrogen-bonded to a chloride and two form a carboxylic dimer, thus giving rise to a 1 : 1 : 4 (1c: NiCl2 :HOAc) stoichiometric ratio. The crystalline 1 : 1 inclusion compound of 2a with 1,4-dioxane suggests a typical clathrate owing to the bulkyness of the host molecule. Graphical Abstract New Pyridylene-bridged Bisoxazoles – Synthesis and Structural Study

1-(5-Acetyl-2-hy­droxy­phen­yl)ethanone

The crystal structure of the title compound, C10H10O3, is characterized by classical intramolecular hydrogen bonding. The hydroxy group is disordered over two positions (77 and 23%). The crystal structure is stabilized via π–π [3.5986 (1) Å] and weak nonclassical C—H⋯O interactions [3.2797 (15) Å].

S,S′-(Pyridazine-3,6-di­yl)dithio­uronium dichloride methanol monosolvate

In the title compound, C6H10N6S2 2+·2Cl−·CH3OH, the pyridazine ring is almost planar, the greatest deviation from the mean plane being 0.025 (2) Å for one of the ring N atoms. The two thiouronium substituents are tilted out of this plane by 60.87 (6) and 57.94 (7)°. The thiouronium cations and the chloride anions are linked by strong N—H⋯Cl hydrogen bonds. The methanol solvent molecule interacts with both the chloride ion (through an O—H⋯Cl hydrogen bond) and the cation (through an N—H⋯O hydrogen bond), resulting in a three-dimensional supramolecular arrangement.